So far, as antagonists to 5-HT.sub.3 receptors, those having an azabicyclo ring moiety described in Japanese Unexamined Patent Publication Nos. Sho 58-978, Sho 59-36675, Sho 61-275276, Hei 1-104072 and Hei 1-106882, those having an imidazole ring moiety described in Japanese Unexamined Patent Publication Nos. Sho 60-214784, Sho 63-211279, Hei 2-131485 and Hei 3-2180, and the like are known.
As result of our diligent study for purpose of finding out such compounds having potent and selective antagonistic action to the 5-HT.sub.3 receptor, the inventors of the present invention have found N,N'-disubstituted amide derivatives which satisfy said purpose and have a different chemical structure from that of known compounds, leading to completion of the invention.